(217fc) Chitosan/MWCNT-Decorated With Agnp Composite: Dielectric and Antibacterial Characterization

Organic/inorganic nanocomposite materials and specifically bionanocomposites represent an emerging group of nanostructured hybrid materials. Bionanocomposites are formed by the combination of natural polymers and organic/and or inorganic solids, they show at least one dimension on the nanometer scale. The use of bionanocomposites has been preferred since most of the synthetic polymers are not biocompatible, so natural polymers such as polysaccharides are ideal components in this type of composite materials. A very attractive bionanocomposite is formed by Chitosan (CTS) and carbon nanotubes (CNTs). This combination is not new, it has been studied for biosensors modification, or focusing on preparation, structural characterization and mechanical properties, however, there is only one study about dielectric properties of this composite. On the other hand, recently CNTs have been decorated with silver nanoparticles (AgnP) to enhance their electrical conductivity and subsequently be combined with polymers to fabricate electrically conducting polymer composites. Chitosan films doped with CNTs-decorated with silver nanoparticles (AgnP) have been developed and represent an improved material for its application as biosensor, in our knowledge this is the only one study regarding this combination. Therefore a detail characterization about its dielectric properties has not been performed so far and neither a comparison with that of the CTS/CNT composites without silver decoration. This way, the dielectric characterization of this composite is a promising investigation area and it will be helpful to understand some specific behaviors and differences of these composites.

This work presents dielectric relaxations analysis of CTS/CNT and CTS/CNT-AgnP composites. The conductivity of pristine chitosan is considerable increased with the incorporation of the fillers, however, strong chemical interactions between CNT and AgnP (identified by FTIR analysis) directly affects dielectric properties of CTS/CTN-AgnP composites, since the percolation threshold is very closed but still not observed at concentrations as higher as 4 wt% when compared with CTS/CNT composites and the characteristic α-relaxation process related to glass transition phenomena vanishes nearby the critical concentration of percolation threshold in both combinations (CTS/CNT and CTS/CNT-AgnP) as a result of the metallic type conduction. The glass transition temperature of pristine CTS is increased as filler´s concentration increases regardless the type of filler as a result the restricted motion of polymer's backbone because of the fillers inclusion. Finally, the antibacterial activity analysis suggests potential applications of these composites where hygiene is a key factor.